Consuming 4 liters oil per 600km!

[after oil]

and the valves for each cylinder were closed as you tested each cylinder

I am not sure 100% that the cylinders what at TDC

Perhaps the shop left off all the intake valve stem seals?

should i take the stupid head off and bring it back to that place that resurfaced and regrinded it?

Did the dipstick get damaged or replaced? I'm thinking perhaps a three liter overfill might get that symptom.

i dont think so, ive driven hundreds of miles and always need to replace the oil

[asavage]

and the valves for each cylinder were closed as you tested each cylinder

I am not sure 100% that the cylinders what at TDC

When you put shop air in, if a valve was open (even a little bit), you would hear hissing at either the air filter (throttle body, if the plenum is off) or the exhaust pipe outlet, wherever that is. If no hissing, then the valves are closed.

Perhaps the shop left off all the intake valve stem seals?

should i take the stupid head off and bring it back to that place that resurfaced and regrinded it?

No. You can see the valve stem seals by removing the valve cover and looking between the coils of the springs. I have replaced them with the head on, on my first '82 720 SD. It's relatively easy -- though a bit messy -- to do (install or replace the valve stem seals) if you follow one important rule on the SD: always have the piston at TDC of the cylinder you are working on the valves. The valve cannot drop into the cylinder if the piston is at TDC.

Anyway, with a good flashlight and a few minutes, you can look between the valve springs' coils and ascertain whether there are valve stem seals installed. I don't know why there wouldn't be -- any competent shop wouldn't leave them out -- but we are double-checking their work now.

Did the dipstick get damaged or replaced? I'm thinking perhaps a three liter overfill might get that symptom.

i dont think so, ive driven hundreds of miles and always need to replace the oil

If the wrong dipstick is used, or the dipstick tube has been altered (not inserted back into the block all the way), you will have to add more oil to get the level to hit the 'F' mark. Say it takes nine quarts to reach that mark. You put nine quarts in, drive. It burns lots of oil due to the oil level being up in the way of the rotating parts now. You add oil when the level is "low" (according to the dipstick). The oil level remains too high, oil consumption continues to be high.

Just guessing, but check to see that the dipstick's outer tube is not hanging out of the block an inch.

[philip]

_SNIP_ I think I am out of useful suggestions. I do not know how you could obtain 400+ PSI compression and have bad oil control rings at the same time. It is burning a lot of oil.

As I said in the beginning ...

"... the rare and elusive 1987 D21/SD25, I have come to believe these trucks exist ONLY in the minds of people who own them. "

[after oil]

ill look at all that today

thanks phillip for a little comic relief!

[philip]

_SNIP_ I think I am out of useful suggestions. I do not know how you could obtain 400+ PSI compression and have bad oil control rings at the same time. It is burning a lot of oil.

Just throwing it out ... not saying precisely ... just saying...

Let's imagine an oil ring broken and/or caked with carbon (afterall these oil rings are a single type (not rails). So oil floods to the compression rings ... passing the compression rings when the piston is moving down during air Intake. Add on when the intake air is "throttled" close while cruise down vehicle speeds.

Let's imagine how that 500 psi cylinder too. How does one get excessive air compression? How about this wild thought? Let say the Intake valve is closing sooner that normal (ie a worn cam lobe on both ramp sides)(of course, total lift would be less).

SVO damage effect?

[asavage]

I can't tie cam lobe wear specifically with alternative fuel operation, that's a stretch at this point.

The problems began with the head gasket replacement.

[philip]

I can't tie cam lobe wear specifically with alternative fuel operation, that's a stretch at this point.

The problems began with the head gasket replacement.

(again) Try tie intake valve close point to crank compression psi, refering to "after oil" his 500 psi reading.

His oil ring?

[asavage]

I'm not following you . . . Intake valve closing sooner than normal? Caked oil rings? How does this relate to sudden oil consumption gain?

[philip]

I'm not following you . . . Intake valve closing sooner than normal?

(A thought)Let's imagine how that 500 psi cylinder too. How does one get excessive air compression? How about this wild thought? Let say the Intake valve is closing sooner than normal (ie a worn cam lobe on both ramp sides)(of course, total lift would be less). .

Caked oil rings? How does this relate to sudden oil consumption gain?

(A second thought)"Let's imagine an oil ring broken and/or caked with carbon (afterall these oil rings are a single type (not rails). So oil floods to the compression rings ... passing the compression rings when the piston is moving down during air Intake. Add-on when the intake air is "throttled" close while cruise down vehicle speeds.

[asavage]

Yes yes yes . . . but how did all this change when he replaced the head gasket?

He removed all excess carbon from the piston tops when the head was off, and the head has been cleaned: no compression-raising carbon in combustion chamber.

The oil control rings didn't suddenly become caked/coked/discombobulated in one week. And why weren't the other rings affected (see compression pressures)?

Cam lobes worn? Maybe . . . but unrelated to high oil consumption.

[philip]

Yes yes yes . . . but how did all this change when he replaced the head gasket?

That was only your thought ... mine is a different walk.

He removed all excess carbon from the piston tops when the head was off, and the head has been cleaned: no compression-raising carbon in combustion chamber.

The oil control rings didn't suddenly become caked/coked/discombobulated in one week. And why weren't the other rings affected (see compression pressures)?

Recall the PHOTOI made where oil loss appeared to be happening at the corner of one piston crown.

[REDNECK]

ok! i'll bite.........when you cleaned the tops of the pistons befor the head went on ........how did you clean them?.....and what did you use?.......and i'll get killed for this but, why? did you clean them?.............i looked at the pics from the past and it looks like a wire wheel was involved yes?......and wassssup all?...

i read the post and could not belive it my old girl burns 1/2 a liter between oil changes, and i live with that......i change the oil every 4000km(2,485mi).....and use valvoline 15/40.

[after oil]

i knew not to use a wire wheel or machine, and i just used scotch pads and some seirous elbow grease.

as for the intake valve and cam lobe theories, im still processing. starting to get a little over my head maybe, but i'll catch up

[REDNECK]

i'm thinking that you have a head start on most, ........lol!.......alright who's adding the miles conversion to my last post!!!.......hahaha!

as to how it was all removed, sorry dude i had to ask. I've seen a person buff the fire rings off a n14 with a buffer, and i thought that would never be done......you never know.

[philip]

-SNIP- As for the intake valve and cam lobe theories, im still processing. starting to get a little over my head maybe, but i'll catch up

Oh no ! For 1987 D2 / SD25 trucks cannot be used with compression gauges. Nope. For your kind of truck you may only use crankshaft rhythm while the injection pump is set to OFF. If you hear even crankshaft rhythm ... then your compression is acceptable (your starter and/or battery should be ruined by the time you can tell there is at least ONE cylinder that is either excessive high or too low).